Athletic monitoring device

ABSTRACT

An athletic monitoring device for attachment to a portion of an athlete&#39;body or to athletic equipment. The device measures a predetermined parameter of the motion of the device while in use and compares the measured parameter to a predetermined range. Intensity of acceleration is measured by taking the square root of the sum of the squares of acceleration data for each of the three axes of motion. This value is compared to a threshold value. If greater than the threshold value, the square root value is stored and added to a second measured intensity value. In this manner, a sum of intensity values throughout a stroke is calculated. If the sum of intensities is above or below a predetermined range, appropriate signalling will so indicate.

This is a continuation of application Ser. No. 06,576,639 filed on Feb.3, 1984, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention.

The present invention relates to biofeedback devices, and in particular,to such devices for improving athletic performance.

2. Description of the Prior Art.

A biofeedback device monitors a particular human activity and provides"feedback" information to the participant, which indicates some qualityor characteristic relating to the performance of that activity. Theparticipant uses the feedback information to modify or improve theperformance of the activity relative to some standard.

Many such devices have been proposed to improve various sportsactivities such as the golf swing of a golfer, the bowling ball deliveryof a bowler or the swing of a baseball hitter. For example, U.S. Pat.No. 3,301,559 to Jolley describes a wrist-worn device which is intendedto provide an indication as to the particular form which the bowlerexhibits as the bowler bowls the bowling ball. The Jolley device isentirely mechanical in nature and is not readily adaptable to indicatethe correct execution of any bowling form other than the one for whichit is designed. In bowling, there is no one correct form so that theJolley device may not be suitable for many bowlers.

Other devices such as those shown in U.S. Pat. No. 3,815,427 toGladstone and 4,205,535 to Swanson measure the peak acceleration orvelocity of the head of a golf club or a portion of the body such as anathlete's hand. However, for many sports such as bowling, in which thetotal acceleration during a certain interval is an important factor, ameasurement such as the peak velocity or peak acceleration of themovement may not be particularly helpful in encouraging consistency ofthe overall movement of the arm or wrist.

Kleinerman, U.S. Pat. No. 4,330,123, describes a wrist-worn device whichemits an audio signal when the bowler's arm reaches a pre-determinedattitude. This predetermined attitude is not readily changeable in theKleinerman device such that the device may not be suitable for allbowling styles. Furthermore, the Kleinerman device apparently emits asignal only when the desired attitude (or a predetermined approximationthereof) is achieved. The range of attitudes at which the Kleinermandevice will emit a "correct attitude" signal is also not readilychangeable by the bowler. Thus, the Kleinerman device might be toofrustrating for use by beginners if the predetermined range is too smallor may be useless for highly skilled bowlers if the predetermined rangeis too large. Still further, the Kleinerman device apparently providesno indication as to whether the attitude of the bowler's arm followingthe release of the ball was either too high or too low, but merelywhether or not the attitude was correct.

Still another athletic monitoring device is shown by Evans, U.S. Pat.No. 3,788,647. This device has a plurality of accelerometers formeasuring the swing of an athlete's arm. The data sensed by theaccelerometers are transmitted to a receiver for comparison andanalysis. Thus, the Evans device is not fully self-contained and maytherefore be impractical for many applications where a receiver cannotbe accommodated.

SUMMARY OF INVENTION

It is an object of the present invention to provide an athleticmonitoring device obviating, for practical purposes, the above-mentionedlimitations.

The present invention provides a fully self-contained athleticmonitoring device which is sufficiently portable to be worn about thewrist of an athlete. The device measures a predetermined parameter ofthe motion of a portion of an athlete's body or the motion of a portionof athletic equipment being moved by the athlete. This measuredparameter is compared to a predetermined range and a signal is providedto the athlete to indicate the results of that comparison. In onefeature of the present invention, the device has user operable inputs bywhich the athlete can set the predetermined range in accordance with hisparticular style and skill level. Consequently, an athlete of relativelylow skill can input a relatively large range and, as his consistencyimproves, the athlete can narrow the range. Thus, the device is suitablefor use by athletes of varying skill levels.

In another feature of the present invention, the device provides a firstaudio signal if the measured parameter exceeds the predetermined rangeand also provides a second audio signal if the measured parameter isless than the predetermined range. In the illustrated embodiment of thepresent invention, the parameter measured by the athletic monitoringdevice is the vigor or intensity by which a bowling bowl is bowled. Ifthe bowling ball is bowled within the predetermined range, a thirdsignal is emitted, which in the illustrated embodiment, is a silentsignal. By having three different audio signals which indicate whetherthe ball was thrown too hard, too soft, or within the pre-determinedrange, the learning efficiency of the user is increased and the user canachieve a more consistent bowling motion faster. Furthermore, the audiosignal obviates the need for the bowler to look at the device in orderto determine whether the intensity of the ball delivery was within therange, increasing the convenience of the device.

In the illustrated embodiment of the present invention, the athleticmonitoring device has sensors for sensing the acceleration of the bodyor equipment portion while in motion. The sensed acceleration data iscollected over an interval of the motion being measured so that themeasured intensity is not a peak measurement but is, instead, a functionof all the acceleration data collected over the interval. Such ameasurement parameter is often more indicative of the desired overallmotion than are peak measurements.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial view of a wrist-worn athletic monitoring device inaccordance with a preferred embodiment of the present invention;

FIG. 2 is a schematic diagram of the internal physical layout of variouscomponents of the module of the device in FIG. 1;

FIG. 3 is a schematic diagram of the electronic circuitry of the deviceof FIG. 1; and

FIGS. 4A and 4B are flow-charts illustrating the programming of themicroprocessor of the circuit in FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to FIG. 1, an athletic monitoring device in accordancewith a preferred embodiment of the present invention is indicatedgenerally at 10. The device 10 is a wrist-worn monitoring device whichmeasures the intensity or vigor by which a bowler bowls a bowling ball.The measured intensity is a function of the total acceleration of thedevice over a particular interval of the bowling delivery motion. It isrecognized that the device may be used to measure the intensity of othermotions such as the movement of the wrist of a billiard player driving abilliard cue forward, or adapted to measure the motion of the head of agolf club. It should be further recognized that the device 10 may bereadily modified to measure other parameters of motion such as thedirection of travel.

The device 10 is worn about the wrist of the bowler's bowling arm andincludes a module 12 and a pair of wrists bands 14a and 14b attached tothe module 12. The wrist bands 14a and 14b are secured about thebowler's wrist by a Velcro fastener carried on the bands 14a and 14b.The wrist band 14a has a loop 16 through which the free end 18 of theother wrist band 14b may be inserted.

The device 10 is activated by means of a pushbutton on/off switch 20.When activated, the device 10 senses the motion of the bowler's wristwhile the bowling ball is being delivered and computes a valuerepresentative of the intensity by which the ball has been thrown. Thiscomputed intensity value is compared to the range of desired intensityvalues which has been preset by the bowler. The device 10 emits a highfrequency audio tone through a speaker 22 if the computed intensityvalue exceeds the preset range of intensity values, a low frequency toneif the computed intensity value is below the preset range and no tone ifthe computed intensity value is within the preset range. Thus, aftereach bowl, the bowler is immediately given a feedback signal in the formof an audio tone or no tone, which indicates whether the bowler hasbowled the ball with an intensity which is within the preset range.

In the illustrated embodiment, the computed intensity value is a threedigit number which is displayed on the module 12 by a 3-digit display24. The preset range is defined by a "set" value and a "window" valuewhich are inputed into the device 10 by the bowler. The set valuedefines the mid-point of the range and the window value defines the sizeof the range centered about the set or mid-point value. For example, aset value of 125 and a window value of 6 defines an intensity range from122 to 128.

The set value is inputted by depressing a pushbutton mode switch 26until the word "SET" appears in an LCD mode indictor display 28 of themodule 12. The set value last inputted into the device 10 is recalledfrom memory and is displayed by the 3-digit display 24. A larger setvalue may be selected by depressing an "up" pushbutton switch 30 whichcauses the number displayed in the display 24 to automatically incrementa unit at a time. When the new desired set value appears in the display24, the up button 30 is released. Similarly, the set value displayed inthe display 24 may be decremented downward by depressing a "down" button32.

There is no one correct intensity set value for all bowlers. Each bowlerbowls the ball with a different intensity depending upon the individualbowler's style, size and strength. To achieve a high score, it is notnecessary that the ball be thrown hard. Consequently, the monitoringdevice 10 of the present invention allows the bowler to input thedesired intensity value in accordance with his or her own bowling style.Set values for men typically vary between 100 and 150, and between 75and 104 for women.

The device 10 compares the measured intensity value computed after eachball delivery with the set intensity value inputted by the bowler, andindicates to the bowler whether the bowler has thrown the ball with anintensity sufficiently close to the preset intensity. By consistentlythrowing the ball with the same intensity which is correct for thatparticular bowler, the bowler can improve his or her score.

The abililty of the bowler to control the consistency of the bowlingmotion depends upon the skill level of the bowler. The device 10 allowsthe bowler to input the size of the allowable range about the set valuein accordance with the bowler's ability. The size of the range (orwindow value) is inputted by depressing the mode button 26 until theword "WINDOW" appears in the display 28. The window value last inputtedinto the device 10 then appears in the display 24 and may be incrementedor decremented as desired by depressing the up and down buttons 30 and32, respectively, as described above in connection with the inputting ofthe set value. For bowlers capable of averaging a bowling score inexcess of 200, a window value of 6 to 8 may be appropriate whereas a 150score bowler would likely find a window value of 12 appropriate. Abowler whose bowling score usually falls below 150 should input a stilllarger window value. After inputting the set and window values definingthe desired range, the bowler depresses the mode button 26 until theword "BOWL" appears in the display 28, indicating that the device isready to measure and compare the intensity of the bowler's bowlingmotions.

FIG. 2 is a schematic diagram of the internal layout of the module 12 ofthe device 10. Mounted within the housing 36 of the module 12 are threeaccelerometers 40-42 for measuring the acceleration of the device 10 inthree orthogonal axes of motion designated X, Y and Z, respectively. Theaccelerometer 40 has a light-emitting diode (LED) 44a which is alignedto illuminate a pair of photovoltaic cells 46a and 48a. Theaccelerometers 41 and 42 similarly comprise an LED (44b, 44c) and a pairof photovoltaic cells (46b, 46c and 48b, 48c (not shown)).

Each accelerometer further has a mass 50a-50c which is suspended by aspring 52a-52c between the LED and the pair of photovoltaic cells of theaccelerometer. Each spring resiliently supports the associated mass in amanner which substantially restricts the motion of the mass to a singleplane. The masses 50a-50c and springs 52a-52c are mounted in the housing36 of the module 12 so that the three planes of motion of the masses50a-50c are oriented orthogonally.

These three orthogonal planes contain the three mutually orthogonal X, Yand Z axes of motion. If the module 12 is accelerated along the X axesthe mass 50a is also deflected along the X axis (in the oppositedirection) against the resiliency of the spring 52a. Accelerations ofthe module 12 along the Y and Z axes produce corresponding motions ofthe masses 50b and 50c, respectively. Each of the three masses 50a-50care positioned between the associated LED and pair of photovoltaic cellssuch that the mass shades approximately 50% of each photovoltaic cell ofthe accelerometer from the illumination of the associated LED.Acceleration of the module 12 along the X axis deflects the mass 50asuch that the proportional shading of the photovoltaic cells 46a and 48aof the accelerometer 40 is changed. Each photovoltaic cell has an outputvoltage which is dependent upon the incident light on that cell.Consequently, the acceleration of the mass 50a along the X axis may besensed by comparing the relative voltages produced by the photovoltaiccells 46a and 48a. Similarly, the acceleration of the masses 50b and 50cin the Y and Z axes, respectively, may be sensed by comparing therelative voltage outputs of the pairs of photovoltaic cells of theaccelerometers 41 and 42, respectively. It is recognized that othertypes of accelerometers such as the "G-Clip" accelerometers sold byINSOUTH ELECTRONICS may be used.

The relative voltages of the photovoltaic cells of the accelerometers40-42 are compared and processed by processing circuitry 60 (FIG. 3)carried on a circuit board 56 mounted within the housing 36. The module12 also includes a battery compartment 58 in one corner of the housing36.

FIG. 3 shows an example of the circuitry 60 which processes the outputsignals of the accelerometers 40-42 as shown in FIG. 2 generate a valuewhich is representative of the intensity by which the bowling ball wasbowled. The processing circuitry 60 also compares the measured value tothe desired range inputted by the bowler and outputs an audio signal inaccordance with that comparison as previously described. The processingcircuitry 60 includes three differential amplifiers 62a-62c, each ofwhich has an inverting input coupled to an output of one of thephotovoltaic cells 46a-46c of each pair of the accelerometers 40-42. Theoutputs of the other photovoltaic cells 48a-48c of the cell pairs arecoupled to the non-inverting inputs of the amplifier 62a-62c,respectively.

The amplifier 62a produces an analog voltage signal at an output 64a,the magnitude and polarity of which is representative of theacceleration of the module 12 along the X axis. Similarly, theamplifiers 62b and 62c produce voltage signals at outputs 64b and 64crespectively, which are representative of the acceleration of the module12 along the Y and Z axes, respectively.

The processing circuitry 60 further includes a microprocessor 66 and amultiplexer 68. In the illustrated embodiment, the microprocessor 66 isan Intel 80C48 CMOS integrated circuit. The multiplexer 68 selectivelycouples one of the amplifier outputs 64a-64c, to the non-inverting inputof a comparator circuit 70. The microprocessor 66 has a three-bit outputbus 72 coupled to the control input of the multiplexer 68 to control theselection of the amplifier outputs.

The microprocessor 66 converts the analog voltage from the selectedamplifier to a digital representation utilizing the successiveapproximation technique in the illustrated embodiment. A machinelanguage program for programming the microprocessor 66 is set out in theAppendix. The microprocessor 66 outputs an 8-bit digital representationat an 8-bit output bus 74, which approxmates the analog value to beconverted. The bus 74 is coupled to the input of an 8-bit R/2R laddercircuit 76 which converts the 8-bit digital representation to an analogvalue at an output 78. The comparator circuit 70 compares the analogvalue at output 78 to the selected analog acceleration value from themultiplexer output 69 and outputs a logical one or zero at output 80 tothe microprocessor 66 depending upon the comparison of the analogvalues. The microprocessor 66 successively tests and changes each bit ofthe 8-bit representation at output 74 until the analog value of output78 most closely matches the analog acceleration value from themultiplexer 68. In this manner, the microprocessor converts the analogacceleration value to a digital representation.

The microprocessor 66 in accordance with the internal program of themicroprocessor, computes a value from the collected digital accelerationdata, which indicates the intensity with which the ball was bowled. Thiscomputed intensity value is displayed by the three-digit display 24(FIG. 1) after the ball has been released. The microprocessor 66 outputsthe computed intensity value at an output 82 which is coupled to adigital display driver circuit 84. The driver circuit 84 drives thethree-digit display 24 of the module 12 as controlled by themicroprocessor 66.

The computed intensity value is also compared to the preset intensityrange input by the bowler. The microprocessor 66 has three inputscoupled to the mode input switch 26, the up switch 30 and the downswitch 32, respectively for inputting the desired range. As previouslymentioned the bowler selectively actuates the switches 26, 30 and 32 toinput the set and window values defining the desired intensity range.When the switch 26 has been depressed a sufficient number of times toplace the device 10 in the set mode, the microprocessor 66 reads thelast stored set value from memory and displays it on the three-digitdisplay 24 via the digital display driver 84. The microprocessor 66 thenincrements or decrements the displayed set value in accordance with theactuation of the switches 30 and 32 by the user.

When satisfied with the display set value, the user depresses the modeswitch 26 once more which places the device 10 in the window mode. Atthat time, the microprocessor 66 stores in memory the last displayed setvalue as the new set value for the intensity range, and reads the laststored window value from memory and displays it at the display 24. Theuser may modify the displayed window value as before with the up anddown switches 30 and 32. When satisfied with the displayed window value,the user depresses the mode switch 26 once more which causes themicroprocessor 66 to store the last displayed window value in memory asthe new window value defining the range.

The device 10 has an additional mode designated the test mode. In thismode, the "BOWL", "SET" "WINDOW" and "TEST" indicia are all activated sothat the user can verify that the display 28 operates properly.Furthermore, a calibration number is displayed in the display 24 whichindicates whether the accelerometers 40-42 and the processing circuitry60 are operating properly.

When placed in the bowl mode, the microprocessor 66 computes theintensity of each bowling motion and compares the measured intensityvalue to the intensity range inputted by the bowler. The microprocessorhas an output bus 85 coupled to a two-tone audio signal generatorcircuit 86, the output of which is connected to the speaker 22 of thedevice 10 (FIG. 1). If the measured intensity value is within the presetrange, no tone is sounded. Otherwise, a high frequency tone is soundedif the intensity range is exceeded, and a low frequency tone is soundedif the measured intensity value is below the intensity range.

In the illustrated embodiment, the measured intensity value is computedin accordance with the following expression: ##EQU1## where I is themeasured intensity value, the variables x, y and z are measuredacceleration values along the X, Y and Z axes, respectively, and thequantity T₁ is a predetermined threshold value. The intensity value I ismeasured over an interval of the bowler's swing which is initiated attime t₁ defined as when the quantity (x² +y² +z²)1/2 is found to begreater than the threshold T₁. The measurement interval is terminated att₂ when the measured quantity (x² +y² +z²)1/2 is found to fall below thethreshold T₁.

FIGS. 4A and 4B are flow charts which describe the operation of theprocessing circuitry 60 in the bowl mode. Referring first to FIG. 4A,the microprocessor 66 upon the start of the bowl mode, initializes theprocessing circuitry 60 as indicated in the instruction block 90. Inthis step, the microprocessor 66 clears data memory locations andinitializes the multiplexer 68 to couple the output line 64a of theX-axis differential amplifier 62a to the comparator 70. Upon completionof these tasks, the program proceeds to instruction block 92 at whichthe microprocessor 66 waits for a "data ready" flag to be set. This flagis set by a data acquisition subroutine which is flow-charted in FIG.4B.

The data acquisition subroutine is called by an interrupt signal whichin the illustrated embodiment, is generated by a clock circuit everythree milliseconds. When called, the data acquisition subroutine samplesthe acceleration of the module 12 in one of the three axes of motion asindicated in instruction block 94 of FIG. 4B. As previously mentioned,the multiplexer 68 is initially set to input the analog voltage signalfrom the first differential amplifier 62a to the comparator 70.Consequently, the X axis analog acceleration value is first inputted bythe multiplexer 68. The microprocessor 66 converts this value to adigital representation and squares it in accordance with the expressionset forth above.

Proceeding to the next instruction block 96, the microprocessor adds thesquared digital acceleration data to a memory location in which the sumof the squares acceleration data of all three axes is totaled andstored. A second memory location which contains a pointer number whichcontrols the multiplexer 68, is then incremented so that the analog datafrom the next accelerometer is inputted the next time the dataacquisition subroutine is called.

Proceeding to decision block 98, if all three axes have not beensampled, control is returned to the routine of FIG. 4A such that themicroprocessor program state is returned to decision block 92. There,the microprocessor will continue waiting until the next clock driveninterrupt signal is received which calls the data acquisition subroutineagain. Since the pointer number was previously incremented, theacceleration data from the Y-axis accelerometer is converted to adigital representation, squared and added to the acceleration datamemory location in instruction block 96. After the subroutine of FIG. 4Bhas been called three times so that the data memory location has thedata total for all three axes, control proceeds to instruction block 100at which the data ready flag is set. In addition, the square root of thedata in the data memory location is computed and moved to a newlocation. The previous acceleration data memory location is then clearedfor the next acceleration data samples.

With the data ready flag set, the program proceeds to decision block 104(FIG. 4A) in which the computed acceleration data (x² +y² +z²)1/2 iscompared to a predetermined threshold T₁. The value of the threshold T₁is selected to be approximately equal to the acceleration normallyexerted on the masses 50a-50c by the earth's gravitational field, plus apredetermined margin value. If the acceleration data is greater than thethreshold T₁, the module 12 is considered to be experiencingacceleration resulting from movement of the module 12 in addition to theearth's gravitational field. Thus, if the computed acceleration data isgreater than the threshold T₁, the decision block 104 passes control tothe instruction block 106 where the acceleration data (less thethreshold T₁) is added to a memory location which stores the accumulatedtotal of the acceleration data during the bowling motion in accordancewith the expression (A) above. Then, a "bowl" flag is set (instructionblock 108) which indicates that the bowler's wrist is considered to bein motion. In addition, the data ready flag is cleared. Control is thenpassed back to the instruction block 92 where the microprocessor waitsfor the data ready flag to be set again, indicating that the dataacquisition subroutine has been called three more times by which theacceleration on the three axes is sampled again.

The processing circuitry 60 continues cycling through the instructionblock 92, decision block 104, and instruction blocks 106 and 108,collecting additional acceleration data for the three axes and addingthe computed data to the accumulated total until the computedacceleration data is found to be less than the threshhold T₁ by thedecision block 104. At that time, control passes to a second decisionblock 110 which tests the bowl flag to see if it has been set. If so,the receipt of a computed acceleration data which is lower than thethreshhold T₁ marks the end of the measurement interval and the datatotaled in instruction block 106 is the measured intensity value I ofthe bowling motion in accordance with expression A above.

The measured intensity value I is compared to the desired intensityrange in instruction block 112. If the measured intensity value I iswithin the range preset by the user, no tone is emitted. However, if themeasured intensity range exceeds the preset range, a high frequency toneis emitted (block 114), and a low frequency tone is emitted if themeasured intensity value falls short of the input range. However, if themeasured intensity value is less than 50 percent of the set value, thecollected acceleration data is considered to be a "false trigger" and notone is emitted. In this manner, the device 10 is able to distinguish anormal bowling motion from the haphazard movements of the bowler's armwhile the device is in the bowl mode.

It will, of course, be understood that modifications of the presentinvention, in its various aspects, will be apparent to those skilled inthe art, some being apparent only after study, others being merelymatters of routine electronic and mechanical design. For example, thedevice of the present invention may be modified to measure parameters ofmotion other than the intensity of the motion and may be adapted to beattached athletic equipment such as golf clubs and bats. In addition,the processing circuitry 60 may be manufactured as a hybrid or a singlemonolithic chip. Other emodiments are also possible with their specificdesigns dependent upon the particular applications. As such, the scopeof the invention should not be limited by the particular embodimentherein described but should be defined only by the appended claim andequivalents thereof. The features, of the invention are set forth in thefollowing claim.

We claim:
 1. A wrist-worn bowling monitoring device for monitoring thebowling motion of a bowler, comprising:sensor means for sensing theaccleration of the device in three orthogonal axes of motion andproviding data representative of the acceleration of the device in thethree axes of motion; first computation means for computing values equalto the square root of the sum of the squares of the acceleration data ofeach direction; first comparison means for comparing each of saidcomputed values the to a predetermined threshold; second computationmeans for adding each computed value which exceeds the predeterminedthreshold to provide a total; second comparison means responsive to thefirst comparison means for comparing the computed total to apredetermined range if a computed value is found to be less than thethreshold; signal means for providing a first signal if the computedtotal exceeds the predetermined range and a second signaldistinguishable from the first signal if the computed total is less thanthe predetermined range; and bowler operable input means for inputting adesired total value and a window value, wherein the predetermined rangeis defined as the desired total value less one-half the window value tothe desired total value plus one-half the window value.